Plasma-addressed liquid crystal display panels, commonly referred to as "PALC" display devices, comprise, typically, a sandwich of: a first substrate having deposited on it parallel transparent column electrodes, commonly referred to as "ITO" columns or electrodes since indium-tin oxides are typically used, on which is deposited a color filter layer for a color display; a second substrate comprising parallel sealed plasma channels corresponding to rows of the display crossing all of the ITO columns each of which is filled with a low pressure ionizable gas, such as helium, neon, or argon, and containing spaced cathode and anode electrodes along the channel for ionizing the gas to create a plasma, which channels are closed off by a thin transparent dielectric sheet; and an electro-optic material such as a liquid crystal (LC) material located between the substrates. The structure behaves like an active matrix liquid crystal display in which the thin film transistor switches at each pixel are replaced by a plasma channel acting as a row switch and capable of selectively addressing a row of LC pixel elements. In operation, successive lines of data signals representing an image to be displayed are sampled at column positions and the sampled data voltages are respectively applied to the ITO columns. All but one of the row plasma channels are in the de-ionized or non-conducting state. The plasma of the one ionized selected channel is conducting and, in effect, establishes a reference potential on the adjacent side of a row of pixels of the LC layer, causing each LC pixel in the row to charge up to the applied column potential of the data signal. The ionized channel is turned off, isolating the LC pixel charge and storing the data voltage for a frame period. When the next row of data appears on the ITO columns, only the succeeding plasma channel row is ionized to store the data voltages in the succeeding row of LC pixels, and so on. As is well known, the attenuation of each LC pixel to backlight or incident light is a function of the stored voltage across the pixel. A more detailed description is unnecessary because the construction, fabrication, and operation of such PALC devices have been described in detail in the following U.S. and EP patents, and publication, the contents of which are hereby incorporated by reference: U.S. Pat. No. 4,896,149; 5,077,553; 5,272,472; 5,276,384; 5,349,454; EP 0 500 084 A2; EP 0 500 085 A2; EP 0 554 851 A1; EP 0 597 432 A1; and Buzak et al., "A 16-Inch Full Color Plasma Addressed Liquid Crystal Display", Digest of Tech. Papers, 1993 SID Int. Symp., Soc. for Info. Displ. pp. 883-886.
The second substrate, herein called the "channel substrate", is typically fabricated by etching channels in a thick first glass sheet and patterning parallel electrodes within these channels. Various ways of doing this are described in the referenced patents and publication and in the two referenced related applications. A second thin glass sheet, serving as the thin dielectric sheet to close off the channels, is then placed on top of the first glass sheet and attached to it by using a glass frit seal at the periphery. The ITO electrodes and the LC portion of the display is then fabricated on top of this structure to form the display shown in the referenced publication. The thickness of the thin glass sheet is typically about 30 to 50 .mu.m. The frit sealing process can introduce a lot of uneven stress in this thin sheet, which makes it difficult to carry out certain processing steps on the thin sheet after the frit sealing process. For example, it would be useful to reduce the thickness of the thin sheet even further by etching it after the frit sealing process. The thinner sheet resulting will reduce the voltage required from the drive electronics and simplify the electronics. However, uneven stress in the thin sheet leads to uneven etch rates, which can differ by a factor of 5. Such different etch rates could lead to non-uniform thicknesses across the sheet, which would lead in turn to unacceptable variations in performance across the display.